The present invention relates to an acceleration operating device (hereinafter referred to as an operating device) and more particularly, to an operating device having three or more operating systems which are independently operated without interference with each other provided in a lawnmower and the like.
Hitherto, a throttle valve of an engine mounted on a lawnmower and the like is generally controlled with a control cable (hereinafter referred to as a cable). An operating device for operating the cable has three take-up cable pulleys which are rotatably and concentrically supported by one shaft, as disclosed in Japanese Unexamined Patent Publication No. 210336/1983, Japanese Unexamined Utility Model Publication No. 87725/1985, Japanese Examined Patent Publication No. 61054/1990 and Japanese Examined Patent Publication No. 21732/1991. The three pulleys are independently rotatable. One positioned in the medium of the three pulleys, called the "output-pulley", winds a cable connected to a throttle valve. The other pulley, positioned in one side of the output-pulley, called the first pulley, winds a cable for the first operating (hereinafter referred to as the first cable connected to an accelerator pedal. The other pulley, positioned in the other side of the output pulley, called the second pulley, winds a cable for the second operating (hereinafter referred to as the second cable) connected to a power take-off lever, and the like. Generally, each of the first pulley and the second pulley has a return-spring which puts the pulley back in the beginning position thereof when operating force has been cancelled.
Then, the power take-off lever is employed to connect the output portion of the engine with a power take-off shaft (generally called as PTO shaft) and to simultaneously accelerate the engine revolution. The PTO shaft transmits the engine power to an implement.
Cooperation of the output pulley and the first pulleys and cooperating of the output pulley and the second pulley are performed by engaging of engaging projections and engaging holes thereof. Each of the engaging holes is shaped as, for example, circularly elongated slit ("C" shaped hole) so that the engaging projection can be moved, smoothly, through the predetermined angle by pulling the first cable with operating the accelerator pedal. Thereby the output pulley can be rotated, with rotating of the first pulley, by operating the first cable without interfering with the second pulley. On the other hand, the output pulley can be rotated, with rotating of the second pulley, by operating of the second cable, without interfering with the first pulley. Thereby, the output pulley rotates and takes up the output cable so as to increase an opening degree of the throttle valve.
Each of the operating devices of the prior art is provided with only two cables for operating, individually, the output cable through the output pulley to control the engine. In short, the operating device of the prior art is composed of only two operating (input) systems and one output system. In the operating device of the prior art, it is very difficult to add more input system without interference with the two input operating systems. Therefore, the operating device of the prior art can not be used in an engine of the type wherein a choking position of a throttle valve is set on a position where an opening degree of the throttle valve is larger than that in full acceling.
An object of the present invention is to provide an operating device on which three or more input systems can be mounted by utilizing a peripheral surface of an output pulley. Further, the object includes to provide the operating device, having a holding mechanism, to hold an operating degree of a throttle valve on a desired position even if an operating force on the added input system is cancelled.